MINDELEFF] CAUSES FOR CHOICE OF MESA SITES 641 
wilder spirits of the nomadic tribes; fields were raided when ripe for 
the harvest, and the fruit of a season’s labor was often swept away in 
anight. It soon became unsafe to leave the village unguarded, as a 
descent might be made upon it at any time when the men were away, 
and the stores accumulated for the winter might be carried off. But 
the detail of a number of men to guard the home was in itself a great 
hardship when men were few and subsistence difficult to obtain. Such 
were the conditions according to the ancient traditions. 
Under the pressure described the little villages or individual houses, 
located primarily with reference to the fields under cultivation, were 
gradually forced to aggregate into larger villages, and, as the forays 
of their wild neighbors continued and even increased, these villages 
were moved to sites which afforded better facilities for defense. 
But through it all the main requirement of the pueblo builder—con- 
venience to and command of agricultural land—was not lost sight of, 
and the villages were always located so as to meet these requirements. 
Generally they were placed on outlying spurs or foothills overlooking 
little valleys, and it should be noted that at the time of the Spanish 
discovery and conquest, three centuries and a half ago, a considerable 
number of the villages were so located. 
There seems to be little doubt that the first troubles of the pueblo 
builders, aside from those arising among themselves, which were not 
sufficiently important to influence their arts or architecture, were 
caused by the advent of some tribe or tribes of Athapascan stock. 
Afterward, and perhaps as late as the beginning of the eighteenth 
century, the Comanche extended their range into the pueblo country, 
and still later the Ute found profit in occasional raids over the north- 
ern border. It is quite probable, however, that in the beginning, 
when pueblo architecture was still in an early stage of development, 
none of the tribes mentioned were known in that country. 
Eventually the housebuilders found it necessary to remove their 
homes to still more inaccessible and still more easily defended sites, 
and it was at this period that many of the mesas were occupied for the 
first time. The country is practically composed of mesas, and it was 
aneasy matter to find a projecting tongue or promontory where a vil- 
lage could be built that would be accessible from one side only, or 
perhaps would be surrounded by cliffs and steep slopes that could be 
scaled only after a long and arduous climb over a tortuous and dif_i- 
cult trail. Building material was everywhere abundant and could 
generally be found within a stone’s throw of almost any site selected. 
Few of the villages at the time of the Spanish conquest were 
located on mesa sites, but numbers of them were on the foothills 
of mesas and sometimes commanded by higher ground. At that time 
Acoma occupied its present location on the mesa summit, one of the 
best if not the best and most easily defended in New Mexico, as the 
